Source : Free On-Line Dictionary of Computing

bring X to its knees
     
        To present a computer, operating system, piece of software, or
        algorithm with a load so extreme or {pathological} that it
        grinds to a halt.  "To bring a MicroVAX to its knees, try
        twenty users running {vi} - or four running {Emacs}."
        Compare {hog}.
     
        [{Jargon File}]